There has been a need for a wiper which wipes the internal walls of tubular members free of liquids, such as drill pipe, tubing, casing, and particularly tubular members having restricted passages, such as internal upset pipe and tubing, in operations such as drilling and workover, so that liquids, such as drilling muds, oil and the like are not spilled on the floor when coming out of the bore to change drill bits or other operations requiring removal of drill pipe, tubing and the like. Spilling of such liquids on the floor is hazardous and drilling muds are quite expensive. A number of proposals have been made in the past to wipe the inside of these tubular members free of liquid; however, these have not been entirely satisfactory.
Patents which relate to various wipers for use inside of pipes or tubes include the following U.S. Pat. Nos.: 1,510,581 to Boynton; 1,732,277 to Owens; 2,257,080 to Turner; 2,460,481 to Abel; 2,740,480 to Cox; 3,058,525 to Humphries; 3,265,133 to Burch; and 4,007,784 to Watson, et al. Of these patents the patent to Cox discloses a pipe wiper having a plurality of bunched flexible discs above a float for wiping the inside of drill pipes as the pipes are being removed from the well.
The patent to Humphries has a plurality of arms extending out and contacting the inner wall of the pipe for holding the Humphries cleaning apparatus in a centralized position.
The remaining patents are illustrative of the state of the art.
The foregoing patent structures and proposals have a number of disadvantages. They cannot readily pass through and clean the interior of restricted openings, such as internal upset tubing or drill pipe, they are not pressure equalized so that when pressures are encountered in the well bore damage to or malfunctioning of the wiper occurs, they are relatively expensive to manufacture and are not readily repairable, they do not include a grappling or fishing head by which the wiper can be removed readily from the tubular member, such as by a wire line and an overshot, and they are not made of materials which avoid explosive conditions in use.
It would be highly advantageous to provide a wiper for wiping liquids from the interior of tubular members as they are removed from a bore hole which overcomes the disadvantages and shortcomings of prior art wipers, such as set forth above.
In U.S. application, Ser. No. 848,966, a related application of Ward M. Haggard, a wiper is disclosed which overcomes some of the foregoing disadvantages.